Front pillars (i.e., A-pillars) on a vehicle are structural members of a body frame positioned between the windshield and the front doors. Conventionally, the front pillars support the roof structure as well and, therefore, must provide substantial support in rollover events. At the same time, the front pillars lie within sight lines of the vehicle operator and need to have a minimal profile to allow the operator to maintain proper vision with respect to the front pillars. Thus, there can be conflicting requirements with respect to the design of the front pillars. To provide a strong structural member for the body frame, each front pillar needs to have a maximum cross-sectional configuration, yet maintain a minimal cross-section for vision purposes.
Commonly, each front pillar is formed as a structural member having a closed cross-section by welding together an outer panel and an inner panel in an overlapping manner. Each of the outer panel and the inner panel typically includes weld flanges for joining the other. The weld flanges also provide for a sealing relationship with respect to both the windshield and the front door that are supported on the front pillars. However, because the weld flanges project outwardly from each front pillar, the traditional flange formation can be restrictive and can result in a correspondingly narrower field of view for the operator from within the passenger compartment.
In conventional vehicle construction, a separate roof rail member is secured at its forward end to an upper end of the front pillar (i.e., on each lateral side of the vehicle). The front pillar and the roof rail together define the forward side and the upper side of a vehicle door opening for ingress and egress to and from the passenger compartment. Like the front pillar, commonly, each roof rail is formed as a structural member having a closed cross-section by welding together an outer panel and an inner panel in an overlapping manner. Each of the outer panel and the inner panel typically includes weld flanges for joining the other. The weld flanges also provide for a sealing relationship with the front door and typically are connected to the roof provided on the vehicle.
Within the door opening, typically one of two types of doors is used, including a door with a sash and a door without a sash. When a door with a sash is used, the sash typically carries one seal that sealingly engages against the outer panel of the A-pillar and the outer panel of the roof rail. A second seal can be provided along the outer-most weld flange of the front pillar and the roof rail for sealingly engaging the sash on the vehicle door. When a door without a sash is used, a seal is typically provided along and connected to the outer panel members, respectively, of the front pillar and the roof rail. This seal then sealingly engages a distal end of the window pane of the sashless door. Thus, for the sashless door, only a single seal is used between the vehicle door and each of the front pillar and roof rail. In conventional designs, sashless door constructions generally apply the same material to all of the involved parts. In addition, the roof and/or windshield are not typically involved in conventional sashless door constructions because the roof and/or windshield are applied to the inner weld flange between the outer panel member and the inner panel member of each of the front pillars and the roof rails.